SMS (Short Message Service) is a wireless service used by means of digital terminals operating in a wireless communication network, by means of which it is possible to transfer text-based (maximum of 160 characters at a time) short messages from one terminal, such as a mobile phone, to another. The service uses a Short Message Service Center (SMSC) for storing and transmitting short messages.
The short message is received after transmission in the short message service center, whose task is to deliver it to the correct target terminal (the B-subscriber). The short message service center sends an SMS Request to a Home Location Register (HLR) in order to locate the receiver. When receiving the request, the home location register responds to the short message service center by reporting, among other things, the accessibility status of the receiver. If the receiver is not accessible, the short message service center stores the message for a certain time. When the receiver activates his/her device, the home location register sends information on this to the short message service center, which sends a message to the service system to be transmitted further to the device. After this, the short message service center receives a confirmation on the arrival of the message at the receiver.
The short message service center functions as storage and a transmitter for short messages. Short messages are divided into mobile originating (MO) and mobile terminating (MT) messages. The MO messages (originating) are transmitted to the short message service center, i.e. they are going to another terminal. The MT messages (terminating) are transmitted to a receiving terminal operating in the communication network being used, i.e. they have left from another terminal or applications.
According to prior art, as the receiver of the short message is to be determined that address (phone number) according to which the receiving terminal is identified in the communication network. This is the procedure even if the receiver and the sender have a mutual contract on the use of certain short numbers, the so-called home call numbers. These short numbers are predetermined numbers used in connection with phone calls, by means of which it is possible to form a connection to the receiver. This kind of use of short numbers in connection with phone calls is described, for example, in the patent publication Fl 98185 of the applicant. In the method according to the publication, an outgoing phone call is connected to a switching exchange, where the number is converted into a number suitable for the communication network on the basis of a short number table. After this, the phone call is directed to the bearer of the short number. The idea of the short numbers is to provide each party desiring a connection, i.e. a caller, with the so-called A-subscriber a short number to be used with the receivers of the phone call, the so-called B-subscribers. This short number is common to substantially all the A-subscribers of the same network provider, but the short number is, however, dependent on the A-subscriber in question. Each A-subscriber must determine the actual numbers of the B-subscribers, which correspond to the short numbers of the A-subscriber in question. A short number comprises a first part common to all A-subscribers, and an identification number (e.g. 020 10y). The identification number in the short number is pre-stored in the A-subscriber-specific database, which is in the use of the mobile switching center, and from which the actual number of the B-subscriber can be determined. According to prior art, it has been possible to use these short numbers only in connection with transmitting phone calls, not in connection with outgoing short messages.